Various developments have been made in connection with the shapes of fan rotor blades. The inventors of this application have developed and filed patent applications for fan rotor blades that sufficiently secure structural strength and improve aerodynamic performance. For example, a related art of Japanese Unexamined Patent Application Publication No. 2007-315303 discloses a fan rotor blade whose detailed structure is as mentioned hereunder.
On a hub side of a rotor blade leading edge, there is formed a vertical hub section that is vertical to an axial center of a fan (an axial center of an aircraft engine). A base end (an inner end in a diametral direction) of the vertical hub section is positioned at a hub end of the rotor blade leading edge. From a top end (an outer end in the diametral direction) of the vertical hub section to a mid-span side of the rotor blade leading edge, there is formed a backward tilt mid-span section. The backward tilt mid-span section tilts backward so that a top end thereof is positioned behind (downstream of) a base end thereof. Further, from the top end of the backward tilt mid-span section to a tip end of the rotor blade leading edge, there is formed a forward tilt tip section. The forward tilt tip section tilts forward so that a top end thereof is positioned ahead of a base end thereof.
The vertical hub section is vertical to the axial center of the fan, and compared with tilting the hub side (hub side section) of the rotor blade leading edge backward without forming the vertical hub section on the hub side of the rotor blade leading edge, a sufficient chord length is secured on the hub side of the fan rotor blade. Since the forward tilt tip section tilts forward, an inflow velocity of air on the tip side becomes slower compared with tilting the tip side (tip side section) of the rotor blade leading edge backward, to thereby reduce a shock wave loss on the tip side of the fan rotor blade. Since the backward tilt mid-span section tilts backward, a barycenter of the fan rotor blade is suppressed from being forwardly biased due to the formation of the forward tilt tip section, to reduce stress around the hub end of the rotor blade leading edge. This results in securing sufficient structural strength for the fan rotor blade and improving the aerodynamic performance thereof such as a hub-side pressure ratio, tip-side fan efficiency, and the like.